The present invention relates to high-density, multiplecontact, conductively shielded electrical connectors which are used in a variety of applications. For example, in aircraft, such connectors are often used to interface wiring from various locations throughout the aircraft with processing circuitry of control units located within an electronics bay of the aircraft.
For convenience and flexibility, it is known to manufacture such connectors in the form of modular assemblies in which one or more connector modules or "modules" are fastened rearwardly of and partially within a shell member. Both the shell member and the modules are manufactured in a variety of standard configurations. The electrical connector assembly as a whole can then be mounted to a bulkhead or other mounting surface for use.
For even greater flexibility, the modules are removably mounted to the shell member. Accordingly, if replacement of a particular module is desired, it is a simple matter to remove the module from the shell member and mount a new module in its place. It is not necessary to replace the modular connector assembly as a whole or to interfere with other modules in the modular connector assembly.
In designing electrical circuitry for such connectors, the circuitry often must be protected from disruptions caused by electromagnetic interference ("EMI") including radio frequency interference ("RFI") entering the system. In addition to protecting or filtering electronic equipment against EMI, there is also a need to protect the equipment against power surges or suppress transients owing to lightning, electrostatic discharges ("ESD") and electromagnetic pulses ("EMP"). The high voltage generated by ESD and EMP can damage sensitive integrated circuits and the like.
Frequently today's electronic circuitry requires the use of high density, multiple contact electrical assemblies. As newer generation of electronics are packed into smaller spaces, the circuits become more susceptible to damage from the above types of energy. There are many applications in which it is desirable to provide a assembly with a filter capability, for example, to suppress EMI; and transient suppression means to suppress lightning, EMP and ESD interference or other undesired energy surges which may affect circuits connected by the assemblies.
Typical of the prior art describing filter modules are U.S. Pat. Nos. 4,820,174 and 4,699,590 which show one or more filter inserts positioned within a conductive shell. Typical of the prior art describing transient suppression inserts is U.S. Pat. No. 4,726,638 which shows a transient suppression system for protecting individual circuit boards.
To retain the convenience and flexibility of the modularity of the modular connector assembly, however, it is desirable that the filter and transient suppression capability be incorporated into the connector assembly in a truly modular manner that will permit full interchangeability between the filter and transient suppression modules, respectively, so that the modules can be connected to appropriate mating connectors or other circuits.
Typical of the prior art including both filter and transient suppression protection is U.S. Pat. No. 4,729,743 assigned to the assignee of the present invention. The connector assembly described in U.S. Pat. No. 4,729,743 includes filter and transient suppression subassemblies mounted entirely within an elongate conductive cylindrical shell member. Grounding paths are provided from the transient and filter subassemblies to the outer shell member by conductive ring members therearound being soldered or bonded by conductive epoxy to the conductive outer shell.
Other prior art grounding techniques for electrical connectors are described in U.S. Pat. Nos. 4,874,337, assigned to the present assignee, and 4,470,657. U.S. Pat. No. 4,874,337 describes a strip of spring fingers for providing grounding connections between metal shells of EMI connectors. The strip is wrapped around a plug-type shell within a recess thereof and is held in place by an elastomeric member, such as a O-ring. U.S. Pat. No. 4,470,657 describes a continuous "bracket-like" grounding and electromagnetic shielding device having axially extending flat fingers for placement in a circumferential shielding cavity formed by an annular groove in an overlapping body portions of mating electrical connectors.
A problem in the prior art has been the difficulty in achieving the proper mounting (and removal) of circuit protective modules, such as filter or transient suppression modules, entirely within an axially elongate main shell member to achieve proper alignment of electrical terminals and provide for grounding to protect the assembled electrical circuity within the modules. Further, ease of module replacement is particularly important in the aircraft environment where space is limited and speed of replacement paramount.
The devices described above provide important advantages in protecting a connector assembly by providing either (or both) filter and transient suppression protection. Nonetheless, none of these devices provides for the advantages of enhanced modularity of the filter and transient modules necessary to protect an electrical connector as accomplished by the present invention. None of the patents described above provides the important advantages of providing a modular connector assembly having EMI filter modules and EMP/ESD/lightning transient suppression protection modules having improved mounting and replacement modularity and electrical grounding characteristics, particularly for high density, multi-contact electrical circuit assemblies. The modules of the present invention include a conductively enveloped subassembly which provides electrical grounding through a ground spring to the main (or outer) shell assembly. The ground spring affixed to each of the modules is replaceable and provides an incremental "float" which facilitates the insertion and removal of each of the modules with regard to the deep cavity of the main shell assembly. It also provides a degree of vibration control between the main shell assembly and the module subassembly shells thereby protecting electrical components within the protective modules.